While the Tycho Brahe Planetarium and Jens Olsen's planetary movement-tracking World Clock often garners most of the astronomy-related attention in the delightful Danish capital city of Copenhagen, not to be overlooked is the Rundetårn (Round Tower), a cylindrical 17th century landmark that's home to Europe's oldest functioning astronomical observatory.
While Rundetårn, completed in 1642 under the rule of Christian IV, is still known as a hotspot for amateur astronomers (the University of Copenhagen moved to more spacious, less light-polluted digs, Østervold Observatory, in 1861), it's how one gets to the tower-topping observatory that's the real fun part. In lieu of a proper staircase, Rundetårn sports a 686-foot equestrian staircase wrapping around the hollow core of the building. This spiraling, 7.5-turn ramp made it easier for astronomers to haul heavy scientific equipment from the bottom of the tower up to the rooftop observatory — with draft animals doing most of the heavy lifting. In 1716, Russian czar Peter the Great most famously ascended the tower via horseback, his wife towed behind in a two-wheeled carriage. In more recent years, Rundetårn's famed ramp has hosted bicycle — and unicycle — races. Aside from stargazing activities and glimpses into Denmark's history as an astronomical heavyweight, Rundetårn is now the site of concerts, art exhibitions and numerous cultural events. As for the views from up top, they remain among the best in Copenhagen.